//给字符串追加感叹号
fun String.addExt02(amount:Int = 1) = this + "!".repeat(amount)

fun Any.easyPrint02():Any {
    println(this)
    return this
}

fun main() {
    //不支持string转any，需要使用泛型
    "abc".easyPrint02().addExt02(2).easyPrint02()
}